Kirkiite is a rare lead-bismuth sulfosalt typically found as microscopic grains or small aggregates within hydrothermal ore deposits. It is best identified through lab analysis or X-ray diffraction, as it is macroscopically indistinguishable from other lead-gray sulfide minerals found in similar geologic settings.

Hardness

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrareLead-Bismuth Sulfosalt Group family

Kirkiite

Hardness: 3
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this kirkiite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch kirkiite with a known reference. Kirkiite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Kirkiite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Kirkiite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: lead-gray, black.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: anhedral grains and granular aggregates.

Often confused with

Kirkiite vs. its common look-alikes — and how to tell them apart in the field.

mineral

Galena

Mohs 2.5

How to tell apart: Streak differs — Kirkiite leaves black, Galena leaves lead-gray.

Often found alongside kirkiite

Minerals reported to co-occur with kirkiite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: Pb₁₀Bi₃Sb₃S₁₄
Mohs hardness: 3
Density: 6.72 g/cm³
Colors: Lead-gray Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Hexagonal
Crystal habit: Anhedral Grains and Granular Aggregates
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Base-metal Veins
Typical price: $50-300 per specimen

Where rockhounds find kirkiite

Classic worldwide localities

Kirki, Greece
Kutná Hora, Czech Republic
Kadzharan, Armenia

Field-hunting tip

Look in hydrothermal base-metal veins country — that is the host setting where kirkiite typically forms. If you start seeing galena, chalcopyrite, pyrite in float, you are in the right ground. Field specimens usually show a anhedral grains and granular aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify kirkiite?+

Mohs hardness is 3. It typically shows a metallic luster. The streak is black. Common colors include lead-gray, black.

Where is kirkiite found?+

Notable localities include Kirki, Greece; Kutná Hora, Czech Republic; Kadzharan, Armenia.

How much is kirkiite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is kirkiite safe to handle?+

It contains toxic constituents. Contains lead and bismuth; handle with care and wash hands after contact. Avoid inhaling dust or powder. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like kirkiite?+

Kirkiite is most often confused with Galena, Cosalite, Kobellite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with kirkiite?+

Kirkiite commonly co-occurs with Galena, Chalcopyrite, Pyrite, Sphalerite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does kirkiite form in?+

Kirkiite typically forms in hydrothermal base-metal veins. Working float back to the host body is the standard way to chase a fresh occurrence.

What is kirkiite used for?+

Kirkiite is used in collector.

Find kirkiite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.